Here is the whole idea that stock rotors and pads are just as good as upgraded ones:
For just a second, forget all our cars have abs. When your out driving and some idiot cuts in front of you or someone goes into your lane, you just slam on the breaks (let the abs do the rest) while steering and trying not to hit anything. The stock setup without the abs has more than enough power to lock up the tires so its not a question of how big your rotors are or how sticky your pads are; the stock setup can already do the thing that takes the most force - lock up the tires (without abs).
So then I throw my new rotors and pads on; there is no improvement in stopping distance. The new setup can do exactly what the old one could only it can do it more efficiently in that I probably don't have to push as hard on the petal to lock up the tires, but nothing really noticeable in an emergency situation.
Now add back the abs and the same thing is true; both the stock system and any upgraded system have the power to kick in the abs and make the real stopping distance that would be measured.
The benefit of the larger rotors, calibers, and pads is that they are more efficient system. More efficient means less waisted energy. Less waisted energy means less heat. Less heat means they can work longer without losing any functionality.
So when your cruising around a track and breaking really hard like every 30 sec, your breaks keep slowing you down just as quickly or close to it. When doing normal everyday driving, you generally do not reach the point where the stock breaking system starts to increase your stopping distance.
With all of that being said, that was just the general idea of it. I am sure there are many people in the forum that can give much more accurate details into what happens when your breaks start to fail from being over-stressed. I created this thread to discuss light weight rotors that can fit on the stock WRX rims. If people want to discuss the reasons why you should or shouldn't upgrade their rotors please start another thread or read about the tons of info on the subject already in these forums.
I would love the know the weight of the stock rotors other than having to take them off and weigh them myself. I would also like any suggestions and weights on rotors that are lightweight and fit under the 02-03 stock rims.
Also another question, are the Eagle HP plus pads really worth the extra $$ over the HPS ones?
And if Ian ever reads this, on that link you gave above, were you referring to the 4000 or the 5000 series dba rotors?
Thanks - YELOWRX